The present invention relates to a thermosensitive recording material, in particular, to a thermosensitive recording material with photo-fixing ability. More precisely, the present invention relates to a diazo-type thermosensitive recording material which colors in response to recording by thermal heads at a certain temperature; which loses coloring ability in the non-recorded areas upon photo-irradiation; and which cannot thereafter be further colored even if heated again.
Thermosensitive recording materials are being used not only for copying material from books and documents, but also as output recording sheets for computers, facsimile apparatus and medical analytical instruments, as well as for thermosensitive-recording-type magnetic tickets and thermosensitive-recording-type labels. Because of the ease of automatic recording, thermosensitive recording materials can also be utilized for securities, merchandise coupons, entrance tickets, certificates, payment slips and the like. However, thermosensitive recording materials for such uses must be image-fixable in order to maintain the integrity of the recorded information.
Conventionally, as an image-fixable thermosensitive recording material, a diazo-type thermosensitive recording material is known, which utilizes the coloring reaction between a diazonium compound and a coupler. In a conventional diazo photosensitive paper, the coloring reaction can be caused to occur, so as to provide sufficiently high image density by use of ammonium water or an alkaline solution as a developer, or by heat application, so long as it is used in a conventional manner with a conventional slow development speed. However, when it is necessary to cause the coloring reaction to occur much more quickly with a thermal head or thermal pen, this conventional diazo-type thermosensitive recording material cannot be used in practice because of its slow thermal response to a thermal head and poor preservability.
Especially in the field of facsimiles, a thermosensitive-recording material with rapid recording (rapid coloring) is required in order to minimize communication costs. Yet, again, this conventional diazo-type material does not satisfactorily meet such a requirement.